MYSQL cheatsheet for DDL, DML

by Abhishek Vaish
Dec 14, 2020



Create a table

    CREATE TABLE User(
        uid INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
        name VARCHAR (50) NOT NULL,
        email VARCHAR (50) NOT NULL UNIQUE,
        password VARCHAR(255) NOT NULL,
        active Bool DEFAULT false,
        pid INT,
        CONSTRAINT FOREIGN KEY(pid) REFERENCES Profile(pid) ON DELETE CASCADE  
    );

Alter a table

    ALTER TABLE Profile ADD Lname VARCHAR(30) NOT NULL AFTER Fname ;
    ALTER TABLE Profile MODIFY contact VARCHAR(10) NOT NULL ;
    ALTER TABLE Profile DROP COLUMN username;
    ALTER TABLE Profile CHANGE COLUMN Fname first_name VARCHAR(30) FIRST ;
    ALTER TABLE User ADD FOREIGN KEY(pid) REFERENCES Profile(pid);

Drop a table

    DROP TABLE table_name;

Truncate a table (delete all entries)

    TRUNCATE TABLE table_name;

Rename a table

    RENAME TABLE old_name TO new_name;

Insert a row

    INSERT INTO User(name,email,password) VALUES ("tom","riddle","tom.riddle@gmail.com");

Update a row

    UPDATE User SET name="Tom Riddle" WHERE email="tom.riddle@gmail.com";

delete a row

    DELETE FROM User WHERE name = "Tom Riddle";